A chuck for a capping machine includes a plurality of chuck members, a biasing member configured to bias the plurality of chuck members radially inward, an abutting portion configured to abut against a top face of a cap, and a plurality of chuck jaws provided on an inner surface of each of the plurality of chuck members to engage knurls of the cap. Each of the plurality of chuck jaws includes a leading flank and a trailing flank. An angle of the trailing flank with respect to an outer circumference of the cap is less than an angle of the leading flank with respect to the outer circumference of the cap.